1. Field of Invention
The present invention relates generally to the field of force monitoring systems and more particularly to a force monitoring system for use in an orthopedic shoe capable of limb load monitoring of forces placed onto a force sensing shoe insert.
2. Description of the Related Art
In the field of force monitoring for orthopedic use, shoe insert devices are available that monitor weight applied onto a limb, with computer analysis available for analyzing weight measurements and triggering alarms depending on the weight and load boundaries programmed into the computer software.
In U.S. Pat. No. 5,269,081, to Gray, a force monitoring shoe is disclosed for monitoring the force applied to a patient's leg, as monitored by a force absorption scheme including a heel platform, and a vibration generator located underneath the middle portion of the user's foot, a force monitoring device, and a signaling system. The force monitoring device senses the applied force on the absorption scheme and compares the forces monitored with desired, pre-selected limits, for feedback signaling to the user.
In U.S. Pat. No. 5,253,654, to Thomas et al., an orthopedic weight monitor is disclosed for detecting the forces imposed on the heel of the foot. The weight monitor includes a flexible pad placed inside a shoe in the heel area, with a thin rigid plate having a foil strain gage underneath the plate and within the pad, with an electronic module attached by electrical wires to the strain gage. The strain gage determines weight bearing values for the heel, and the electronic module issues a warning for weight values exceeding a predetermined limit.
In U.S. Pat. No. 5,323,650, to Fullen et al., a force sensor array is disclosed that is positioned within a user's shoe between the foot and the inner sole of the shoe, with the force sensor array having a multiplicity of individual force sensors. Electronic scanning circuitry is connectable to the force sensor array for indicating the instantaneous force sensed by each of the multiplicity of individual force sensors to allow processing of information to obtain and store force data from the force sensor array.
In U.S. Pat. No. 5,357,696, to Gray et al., an orthopedic device is disclosed for monitoring force applied to a wearer's foot. The shoe insert device includes a pressure sensitive element that produces an electrical signal that is related to the force applied by the wearer's foot. The pressure sensitive element is sandwiched between resilient members that are positioned under the central area of the shoe insert. A feedback signaling device receives electrical signals from the pressure sensitive element, with the signaling device including a electronic circuit module for alerting the user of excessive weight applied to the force sensor array.
Prior shoe insert devices include pads that absorb and monitor forces on specific rear areas and/or front areas of a user's foot, with total downward forces calculated from the weight transferred to the rear areas, or front areas of a user's foot. Prior shoe insert devices do not provide an orthopedic shoe that monitors the differences in weight distribution across a shoe insert foot plate, with resulting measuring of strain created between the rear of a foot plate and the front of the foot plate, with adjustable structures provided within the shoe insert to minimize strain resulting from shoe flex and lateral forces generated by the user's foot. Therefore true force readings for the weight bearing surfaces of the user's foot may not be adequately measured by prior devices.
Accordingly, there is a need for an improved force monitoring system for use in an orthopedic shoe having a shoe insertable force sensing unit that is capable of measuring downward forces imposed by a wearer's weight distribution onto the foot of an injured limb, and capable of measuring the resultant downward forces occurring at any place over the length of the wearer's foot.
Therefore, it is an object of the present invention to provide an improved force monitoring system for monitoring weight applied to a person's foot for diagnosing, training, and healing purposes.
It is another object of the present invention to provide an improved force monitoring system that is incorporated into an orthopedic shoe and includes visual, audible, and/or vibration notification to the wearer of the force monitoring system.
It is another object of the present invention to provide a force monitoring system that includes a force sensing unit that monitors weight imposed at any point along the length of a wearer's foot within an orthopedic shoe.
It is another object of the present invention to provide a force monitoring system that measures weight imposed on a wearer's foot for each step and reports to the wearer any weight imposed on the wearer's foot exceeding pre-selected upper limits, or weights below pre-selected lower limits.